Multi-carrier listen before talk

ABSTRACT

Systems, apparatus, user equipment (UE), evolved node B (eNB), computer readable media, and methods are described for multi-carrier listen before talk operations. In various embodiments, a transmitting device may assign one or more primary carriers to perform listen before talk (LBT) operations, with non-primary carriers performing a channel sensing operation at the end of the LBT operations of at least one primary channel. In various embodiments, the LBT operations at the primary carriers may use a shared random countdown number or an independent random countdown.

PRIORITY CLAIM

This application is a continuation of U.S. patent application Ser. No.15/752,481, filed Feb. 13, 2018, which is a U.S. National Stage Filingunder 35 U.S.C. 371 from International Application No.PCT/US2015/065684, filed Dec. 15, 2015 and published in English as WO2017/030603 on Feb. 23, 2017, which claims the benefit of priority toU.S. Provisional Patent Application Ser. No. 62/205,536, filed on Aug.14, 2015, and entitled “MULTI-CARRIER LBT DESIGN FOR LTE IN UNLICENSEDBAND”, each of which is incorporated herein by reference in itsentirety.

TECHNICAL FIELD

Embodiments pertain to systems, methods, and component devices forwireless communications, and particularly to systems and methods forlisten before talk (LBT) operation and license-assisted access tounlicensed frequencies with multiple carriers for long term evolution(LTE), LTE-advanced, and other similar wireless communication systems.

BACKGROUND

LTE and LTE-advanced are standards for wireless communication ofhigh-speed data for user equipment (UE) such as mobile telephones. InLTE-advanced and various wireless systems, carrier aggregation is atechnology where multiple carrier signals operating on differentfrequencies may be used to carry communications for a single UE, thusincreasing the bandwidth available to a single device. In someembodiments, carrier aggregation may be used where one or more componentcarriers operate on unlicensed frequencies.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A is a block diagram of a system including an evolved node B (eNB)and a user equipment (UE) that may operate according to some embodimentsdescribed herein.

FIG. 1B is a block diagram showing additional aspects of the system,including multiple UEs along with an eNB and access point (AP) that mayoperate according to some embodiments described herein.

FIG. 1C illustrates aspects of an air interface in the system, operatingaccording to some embodiments described herein.

FIG. 2 illustrates aspects of multi-carrier listen before talk,according to some example embodiments.

FIG. 3 is a flowchart illustrating an example method for multi-carrierlisten before talk that may be used with some example embodiments.

FIG. 4 is a flowchart illustrating aspects of multi-carrier listenbefore talk, according to some example embodiments.

FIG. 5 is a flowchart illustrating a method of multi-carrier listenbefore talk, according to some example embodiments.

FIG. 6 is a flowchart illustrating aspects of multi-carrier listenbefore talk, according to some example embodiments.

FIG. 7 is a flowchart illustrating a method of multi-carrier listenbefore talk, according to some example embodiments.

FIG. 8 illustrates aspects of a computing machine, according to someexample embodiments.

FIG. 9 illustrates aspects of a UE, in accordance with some exampleembodiments.

FIG. 10 is a block diagram illustrating an example computer systemmachine which may be used in association with various embodimentsdescribed herein.

FIG. 11 is a block diagram illustrating an example user equipmentincluding aspects of wireless communication systems, which may be usedin association with various embodiments described herein.

DETAILED DESCRIPTION

Embodiments relate to systems, devices, apparatus, assemblies, methods,and computer readable media to enhance wireless communications, andparticularly to communication systems that operate with carrieraggregation and license-assisted access. The following description andthe drawings illustrate specific embodiments to enable those skilled inthe art to practice them. Other embodiments can incorporate structural,logical, electrical, process, and other changes. Portions and featuresof some embodiments can be included in, or substituted for, those ofother embodiments, and are intended to cover all available equivalentsof the elements described.

FIG. 1A illustrates aspects of a wireless network system 100, inaccordance with some embodiments. The wireless network system 100includes a UE 101 and an eNB 150 connected via an air interface 190. UE101 and eNB 150 communicate using a system that supports carrieraggregation and the use of unlicensed frequency bands, such that the airinterface 190 supports multiple frequency carriers and licensed as wellas unlicensed bands. A component carrier 180 and a component carrier 185are illustrated. Although two component carriers are illustrated,various embodiments may include any number of two or more componentcarriers. Various embodiments may function with any number of licensedchannels and any number of unlicensed channels.

Additionally, in various embodiments described herein, at least one ofthe component carriers 180, 185 of the air interface 190 comprises acarrier operating in an unlicensed frequency, referred to herein as anunlicensed carrier. An “unlicensed carrier” or “unlicensed frequency”refers to a range of radio frequencies that are not exclusively setaside for the use of the system. Some frequency ranges, for example, maybe used by communication systems operating under different communicationstandards, such as a frequency band that is used by both Institute ofElectronic and Electrical Engineers (IEEE) 802.11 standards (e.g.,“WiFi”) and third generation partnership (3GPP) standards. By contrast,a licensed channel or licensed spectrum operates under a particularstandard, with limited concern that other unexpected signals operatingon different standards will be present.

Apart from the license assisted access (LAA) operation considered inRelease 13 of the third generation partnership project (3GPP) standard(3GPP release 13, open of Sep. 30, 2012), LTE may also be operated viadual connectivity or the standalone LTE mode which may not require muchassistance from the licensed spectrum Recently, a new LTE basedtechnology “MuLTEfire” has been under consideration, requiring noassistance from the licensed spectrum to enable a leaner, self-containednetwork architecture that is suitable for neutral deployments where anydeployment can service any device. The operation of LTE on theunlicensed spectrum without any assistance from licensed carrier will bereferred to as standalone LTE unlicensed (LTE-U) herein.

As discussed below, when a system operates in an unlicensed spectrum,rules and operations for verifying that the unlicensed channels areavailable provide additional overhead and system operational elementsthat are not present in licensed channels. The sharing of a channel maybe referred to as “fair coexistence”, where different systems operate touse an unlicensed or shared channel while limiting both interference anddirect integration with the other systems operating on differentstandards.

LTE cellular communications, for example, historically operate with acentrally managed system designed to operate in a licensed spectrum forefficient resource usage. Operating with such centrally managed usewithin unlicensed channels where systems not centrally controlled thatuse different channel access mechanisms than legacy LTE may be presentcarries significant risk of direct interference. Coexistence mechanismsdescribed herein enable LTE, LTE-advanced, and communications systemsbuilding on or similar to LTE systems to coexist with other technologiessuch as WiFi in shared unlicensed frequency bands (e.g., unlicensedchannels.)

Embodiments described herein for coexistence may operate within thewireless network system 100. In the wireless network system 100, the UE101 and any other UE in the system may be, for example, laptopcomputers, smartphones, tablet computers, printers, machine-type devicessuch as smart meters or specialized devices for healthcare monitoring,remote security surveillance systems, intelligent transportationsystems, or any other wireless devices with or without a user interface.The eNB 150 provides the UE 101 network connectivity to a broadernetwork (not shown). This UE 101 connectivity is provided via the airinterface 190 in an eNB service area provided by the eNB 150. In someembodiments, such a broader network may be a wide area network operatedby a cellular network provider, or may be the Internet. Each eNB servicearea associated with the eNB 150 is supported by antennas integratedwith the eNB 150. The service areas are divided into a number of sectorsassociated with certain antennas. Such sectors may be physicallyassociated with fixed antennas or may be assigned to a physical area,with tunable antennas or antenna settings adjustable in a beamformingprocess used to direct a signal to a particular sector. One embodimentof the eNB 150, for example, includes three sectors each covering a 120degree area with an array of antennas directed to each sector to provide360 degree coverage around the eNB 150.

The UE 101 includes control circuitry 105 coupled with transmitcircuitry 110 and receive circuitry 115. The transmit circuitry 110 andreceive circuitry 115 may each be coupled with one or more antennas. Thecontrol circuitry 105 may be adapted to perform operations associatedwith wireless communications using carrier aggregation. The transmitcircuitry 110 and receive circuitry 115 may be adapted to transmit andreceive data, respectively. The control circuitry 105 may be adapted orconfigured to perform various operations such as those describedelsewhere in this disclosure related to a UE. The transmit circuitry 110may transmit a plurality of multiplexed uplink physical channels. Theplurality of uplink physical channels may be multiplexed according totime division multiplexing (TDM) or frequency division multiplexing(FDM) along with carrier aggregation. The transmit circuitry 110 may beconfigured to receive block data from the control circuitry 105 fortransmission across the air interface 190. Similarly, the receivecircuitry 115 may receive a plurality of multiplexed downlink physicalchannels from the air interface 190 and relay the physical channels tothe control circuitry 105. The uplink and downlink physical channels maybe multiplexed according to FDM. The transmit circuitry 110 and thereceive circuitry 115 may transmit and receive both control data andcontent data (e.g., messages, images, video, et cetera) structuredwithin data blocks that are carried by the physical channels.

FIG. 1A also illustrates the eNB 150, in accordance with variousembodiments. The eNB 150 circuitry may include control circuitry 155coupled with transmit circuitry 160 and receive circuitry 165. Thetransmit circuitry 160 and receive circuitry 165 may each be coupledwith one or more antennas that may be used to enable communications viathe air interface 190.

The control circuitry 155 may be adapted to perform operations formanaging channels and component carriers used with various UEs. Thetransmit circuitry 160 and receive circuitry 165 may be adapted totransmit and receive data, respectively, to and from any UE connected tothe eNB 150. The transmit circuitry 160 may transmit downlink physicalchannels comprised of a plurality of downlink subframes. The receivecircuitry 165 may receive a plurality of uplink physical channels fromvarious UEs including the UE 101. The plurality of uplink physicalchannels may be multiplexed according to FDM in addition to the use ofcarrier aggregation.

As mentioned above, the communications across the air interface 190 mayuse carrier aggregation, where multiple different component carriers180, 185 can be aggregated to carry information between the UE 101 andthe eNB 150. Such component carriers 180, 185 may have differentbandwidths, and may be used for uplink communications from the UE 101 tothe eNB 150, downlink communications from the eNB 150 to the UE 101, orboth. Such component carriers 180, 185 may cover similar areas, or maycover different but overlapping sectors. The radio resource control(RRC) connection is handled by only one of the component carrier cells,which may be referred to as the primary component carrier, with theother component carriers referred to as secondary component carriers. Insome embodiments, the primary component carrier may be operating in alicensed band to provide efficient and conflict-free communications.This primary channel may be used for scheduling other channels includingunlicensed channels as described below.

FIG. 1B illustrates additional aspects of the wireless network system100 of FIG. 1A. As illustrated, the wireless network system 100 mayprovide multiple UEs 101A, 101B, 101C, and so on with access to abroader network 195 via air interface 190. The network 195 may be anysuitable network, including various wide area networks (WANs) or theInternet. This access may be provided via the eNB 150 discussed above,via a wireless access point (AP) 170 providing wireless communicationsusing a wireless local area network (WLAN) such as IEEE 802.11 mentionedabove, or via both. In various embodiments, a wireless network systemmay include multiple APs in addition to the AP 170, and may includemultiple eNBs in addition to the eNB 150 or small cells in support ofthe eNB 150.

FIG. 1C illustrates WLAN channelization options for a frequency bandfrom 5.17 GHz to 5.33 GHz that may be part of an unlicensed portion ofthe air interface 190. The example channelizations for WiFi 802.11acnodes include a set of 20 MHz channels including a primary 20 MHzchannel 191A and a secondary 20 MHz channel 191B. The otherchannelizations are formed by combining contiguous 20 MHz sub-channelsin a non-overlapping manner. One example channelization includes a 40MHz primary channel 192A and a 40 MHz secondary channel 192B. Anotherchannelization includes an 80 MHz primary channel 194A and an 80 MHzsecondary channel 194B. Another channelization includes a 160 MHzchannel 196. After deciding on a transmission bandwidth, one of thechannels is chosen as a primary channel. The primary channel is chosenby the AP that is communicating with the UE.

A WiFi node performs a clear channel assessment (CCA) and extended CCAprocedure to determine if the unlicensed channel is available for useonly on the primary 20 MHz channel. The CCA and extended CCA procedureconsist of sensing a channel for a predetermined duration and performingrandom back-off. After completion of the CCA and extended CCA procedure,the node only performs sensing just before the potential start oftransmission on all the secondary channels. On the 20 MHz primarychannel, the node detects the start of a valid OFDM packet at or above−82 dBm and holds CCA busy for the duration of the packet if start ofthe WiFi packet is detected via preamble detection. Detection isreferred to as signal detect (SD), and the SD is performed while thenode holds CCA busy for any signal above −62 dBm. The busy check forsignals above −62 dBm is referred to as energy detect (ED). Aftercompletion of CCA on the primary channel, the node additionally performsCCA on the secondary 20 MHz channel with SD at −72 dBm and ED at −62dBm. In one embodiment, SD is performed within 25 μs and ED within 4 μs.This refers to coexistence mechanisms at an AP. In certain embodiments,coexistence at an eNB may operate in various ways to complement APoperation on the same frequency band in the same area serving the sameUEs.

FIG. 2 describes system operations performed by a device, which mayeither be a transmitting eNB or a transmitting UE, for coexistencebetween cellular communications operating under license-assisted access(LAA) and WiFi signals and possibly standalone LTE-U operation. For thepurposes of illustration, FIG. 2 is described with respect to eNBtransmission. The system of FIG. 2 includes four unlicensed channelsused by carriers 202, 204, 206, and 208. The carriers need not beadjacent (e.g., there may be other carriers between the illustratedcarriers, such that an eNB may use unlicensed channels which are notadjacent.) The eNB operates using listen before talk (LBT) operationswhich are independent for each channel but that use limitations toimprove performance. This includes support for synchronous transmissionson multiple unlicensed channels to improve wideband channel access. Thismay be achieved in some embodiments by deferring transmissions on someunlicensed channels until other carriers complete LBT. Additionally,some embodiments may operate with aligned LBT operations among multiplecarriers. In such embodiments, once at least one carrier out of all thepotential transmission carriers starts to transmit, other carriers donot perform a countdown regardless of how severe RF leakage is. Whentransmissions from one or more carriers ends, all the carriers perform apost transmission back-off with a new counter value that is appliedcommonly to all the carriers. This operation can mitigate against theeNB excessively accessing the channel. Allowing simultaneous LBToperations by multiple carriers increases the number of contendingnodes, compared to WiFi operation, where only the primary carrierparticipates in channel contention.

As shown in FIG. 2, carrier 204 is initially occupied by WiFi signal212, with the eNB transmitting LAA signals 210, 214, and 216 oncorresponding carriers 202, 206, and 208 during a first time period 211.When the transmission terminates at a time 228, the eNB generates arandom back-off counter that makes the previously used channelsassociated with the carriers 202, 206, and 208 available for use byother systems and devices. The back-off counter counts during a secondtime period 213 up to a time 232, at which a self-deferral period occursfor a third time period 215 as part of the LBT operation. In variousdifferent embodiments described below, the eNB may perform LBT includingthe countdown of a back-off counter with a subsequent self-deferralperiod for different combinations of channels. In some embodiments, onlya single primary channel may have LBT operations with the back-offcounter and self-deferral in the third time period 215. In otherembodiments, all channels may be sensed for LBT with either shared orindependent back-off counters followed by the self-deferral period aftera first back-off counter reaches zero. In some embodiments, a subset ofmultiple channels may be sensed during a back-off countdown and thedeferral period. Channels which are sensed during the back-off counterand self-deferral periods are referred to as primary channels. For theseprimary channels having LBT, if a signal such as WiFi 218, 220, or 222is sensed during the third time period 215, that carrier is not usedduring the next transmission by the eNB. When the LBT operations end ata time 236, a channel sensing is performed on all available non-primarychannels during a fourth time period 217 that ends at time 236 to verifythat the channels are not in use just before a transmit operation. Ifany communication is sensed during the fourth time period 217, thechannels that the communication is sensed on are not used fortransmission during a fifth time period 219. In the embodiment of FIG.2, WiFi 218 is sensed by LBT during the third time period 215 and eitherWiFi 220 or 222 is sensed during LBT or during the channel sensing ofthe fourth time period 217. Because of this, the carrier 204 and thecarrier 206 are not used during the fifth time period 219, while LAA 224is communicated on the carrier 202 and LAA 226 is a transmissioncommunication on the carrier 208. When transmission of LAA 224 and LAA226 end at time 230, the process may either repeat, if additionalinformation is to be transmitted, or the device may go into an inactivemode with no transmissions.

FIG. 3 describes one possible embodiment of LBT operation for LAA orstandalone LTE-U systems. Like FIG. 2 above, FIG. 3 may be performed byeither an eNB or a UE transmitting in a system such as the wirelessnetwork system 100. In operation 302, a device is in an idle state, andin operation 304 the device checks for transmissions. If transmissionsare pending, in operation 308, a channel idle list is checked todetermine if the unlicensed channels in a channel idle list are clearfor a CCA (e.g., LBT) period (e.g., 34 μs). If so, the device transmitsin operation 310 and then determines if additional transmissions areneeded from the device in operation 306. If no additional transmissionsare needed, then the device returns to the idle state in operation 302.If any other transmission is needed after operation 306 or if thechannels are not idle for the CCA period in operation 308, then initialCCA operations 328 end, and extended CCA 330 begins.

In operation 312, a random counter is generated as described above attimes 228 and 230 of FIG. 3. Inputs 326 such as acknowledgements ornegative acknowledgements received by the device may be processed andused to update details of the channels during operation 314. This mayinfluence the generation of the random counter in operation 312. In someembodiments, operation 314 involves selection of a set Q of possiblecounter values between an initial value of X and a final value of Y,such that the random counter generated in operation 312 is a randomvalue selected from the set Q. Inputs 326 may update the X and Y valuesto adjust the possible counters in the set Q. For example, in oneembodiment Q may include the values 3, 4, 5, 6, and 7, where X is 3 andY is 7. In other embodiment Q may include the values 15 to 1023, where Xis 15 and Y is 1023. If Y is adjusted to 5 based on an input 326, then Qis 3, 4, and 5, and after the input the random value will be selectedfrom the new set Q of 3, 4, or 5. In other embodiments, other sets maybe used for the possible values of the random counter used for anylisten before talk or back-off duration that is random. As referred toherein, a random value is any random or pseudorandom value selectedusing a computer or device implemented randomization process. The inputs326 may be based on various types of system feedback. For example, iferrors in transmission are received, a larger back-off period may beused, whereas an absence of errors may result in a smaller back-offperiod. Similarly, a history of recent use by coexisting other devicesmay be used to select a wider range of back-off operations to enablemore generous coexistence and fewer errors from aggressive use of theunlicensed channels.

In operation 316, the device checks to see if a channel is idle duringan extended deferral period, or extended CCA (ECCA or DECCA). If not,the device waits until the channel is clear. When the channel is clear,a countdown and channel sense loop begins to count down from the randomcounter selected in operation 312. In operation 320 the channel issensed, and if it is determined to be busy in operation 324, thedeferral period of operation 316 is restarted. If the channel is notbusy in operation 324, the counter decrements in operation 322. Thisprocess repeats until the counter is identified as zero in operation318, at which point the device transmits on the channel in operation310, and the procedure repeats from an idle state or an expectedfollow-up transmission. The embodiment of FIG. 3 includes independentasynchronous LBT on all component carriers, and so this process is usedindependently for each unlicensed component carrier in a system. Unlikethe process described for FIG. 2, this results in unalignedtransmissions between unlicensed component carriers, and cansignificantly hurt the performance of other devices in the system byusing different channels at unpredictable and unrelated periods. ForWiFi systems competing for multiple channels, if WiFi occupies thesecondary carrier after sensing the primary channel, then as the UE oreNB LAA process independently performs LBT on the secondary carrier,very likely, the secondary channel is occupied by the LAAcommunications. In particular, the amount of time available for grabbingthe secondary channel for WiFi equals the small window over which LAA isperforming CCA. The probability that the WiFi system can grab thesecondary channel is also conditioned on the primary channel success atthe exact window, making it almost infeasible for WiFi to grab thesecondary channel. Such a system for eNB and UE communications thusprovides poor coexistence with WiFi devices. By contrast, variousembodiments of the system operation in FIG. 2 allow aligned usage ofmultiple unlicensed component carriers in ways that allow a WiFi systemto grab a secondary channel (e.g., the channel associated with thecarrier 206) in addition to a primary channel (e.g., the channelassociated with the carrier 204.)

In one embodiment, a device for LAA transmission on multiple unlicensedchannels performs LBT on only one of the component carriers. This onecomponent carrier is referred as the primary carrier out of theavailable component carriers C. The selection of the primary carrier canbe random for every data burst or fixed semi-statically, or cancorrespond to the primary channel of coexisting WiFi systems. Theprimary component carrier completes the LBT described in FIG. 3. A CCAcheck is conducted on all remaining carriers just before completion ofthe LBT on the fixed selected carrier. In some embodiments, the CCAcheck on the primary carrier may be implemented as an extension of theLBT, rather than a separate CCA check, such that the CCA check includesa separate CCA check of the non-primary channels and the end of the LBTon the primary channel. In one of the embodiments the CCA check can beperformed for 25 μs. As additional embodiment, for updating thecontention window Q, negative acknowledgements on all or subset of thecomponent carrier used for transmission of the data burst can be used.

Thus, in one embodiment, a single primary carrier is associated with theoperations of FIG. 3, and the remaining component carriers areassociated with the operations of FIG. 4. Thus, as illustrated by FIG.4, the remaining component carriers begin with a primary channel Pselected in operation 402 and configured for performing independent LBTwith a corresponding back-off counter and self-deferral period. Theremaining carriers wait for a channel sensing operation following theself-deferral period. All channels begin as idle in operation 404. Ifthe component carriers are needed for transmission in operation 406, thedevice checks for an initial idle state of the primary channel and waitsfor this idle state in operation 408 during an initial CAA period(BiCCA). At operation 410, the system determines if a follow uptransmission is to be made after an initial transmission. If not, thenthe system remains in idle state 404. If a follow up transmission is tobe made, a random number is then generated in operation 412 based on anupdated contention window from operation 428. The LBT process for theprimary channel then uses a countdown channel sensing loop in operations420, 422, 426, and 424. If activity is sensed on channel P in operation426 before the countdown reaches zero, then the LBT/DECCA operationrepeats waiting for the primary channel to be idle. If the primarychannel remains idle until the countdown reaches zero, then for eachnon-primary channel, a CCA is performed in operation 418. After the CCAcheck, only idle carriers are used for transmission in operation 414. Ifanother transmission is needed, then the process repeats to generate arandom number in operation 412. A contiguous component carrierconstraint can be imposed on the carrier selection for transmitting thedata burst (after LBT is purposed on the carriers other than the primarycarriers) in some embodiments.

FIG. 5 illustrates aspects of another embodiment. In this embodiment, anLAA device performs LBT on a subset of component carriers, where thesubset includes more than one component carrier. In other words, morethan one primary carrier is used, but possibly not all of the componentcarriers are primary component carriers. The subset of primary carriersmay be fixed semi-statically from the available component carriers aspart of an operation 502. The system then begins with carriers in anidle state at operation 504, transitioning into a need to transmit beingidentified in operation 506, followed by a determination of whichcarriers are to be used for transmission in operation 508. In operation512, the LAA operation generates a single random number N from [0, q−1],where q is configured a priori or adaptively calculated based on anupdated contention. Q may be based on channel errors, acknowledgements,negative acknowledgements, history data for the channel, or any othersuch information from operation 518. As one embodiment, contentionwindows for all primary component carriers are updated independentlybased on the negative acknowledgements, while the common contentionwindow Q can be the maximum of all the contention windows associatedwith the all primary carriers. The primary carriers then perform anindependent LBT operation as described in FIG. 3, but using the singleback-off counter. After the primary LBT/CCA occurs in operation 516, thesystem checks to see if none of the primary carriers are idle inoperation 528. If none of the primary carriers are idle, then sensing isperformed in operations 532 and 536, with an extended CCA (DECCA) checkoperation 522 for non-idle primary carriers while the system waits for afirst idle primary channel. Once an idle primary channel is identifiedfrom the plurality of primary channels in operation 528, then aself-deferral period occurs in operation 530. During the self-deferralperiod of operation 530 (taking Tμs), each primary carrier continues tocheck an idle status using operations 532,536, 534, and 522. Any primarychannel not idle during an iteration of operation for that channelresets the countdown for that channel, and proceeds through a loop,decrementing the counter for that channel in operation 534 when thechannel is idle. Thus, a primary channel can be deemed as idle as longas the counter reaches zero before the end of the self-deferral period,even if it is sensed as non-idle. Operations 526, 524 and 520 thendetermine which carriers to use for transmission at the transmissionoperation 514. If the remaining primary component carriers do notcomplete LBT before the completion of the self-deferral period asmentioned above, only the primary carriers that have completed the LBTare used for transmission. If the LBT on all primary carriers iscompleted before the self-deferral period (e.g., Tμs), a CCA check(e.g., 25 μs duration) is performed on all component carriers which areselected for transmissions, just before completion of the LBT of all theprimary component carriers. In some embodiments, the channel sensingperiod is considered the period just before the end of the LBT for theprimary carriers. After the CCA check on the non-primary carriers, onlyidle carriers (e.g., carriers in the set of idle non-primary carriersand primary carriers that completed LBT before the end of self-deferralperiod) are used for transmission. The process then either returns to anidle state or repeats if additional transmissions are to be made.

FIG. 6 illustrates an additional embodiment of multi-carrier listenbefore talk. In the embodiment of FIG. 6, LAA operations of a deviceonly perform independent LBT operations on a subset of the componentcarriers (referred to as primary carriers) selected from the totalnumber of available component carriers. The selection of the primarycarriers can be random or fixed semi-statically. The primary carrierscan correspond to the primary and secondary channels of WiFi systems insome embodiments. Each of the plurality of primary carriers in such anembodiment independently perform LBT/CCA procedures as described in FIG.3. In this embodiment, an LAA system of a device generates anindependent random number from zero to qc−1 for each component carrier,where qc is the contention window parameter for the correspondingcomponent carrier. A self-deferral period is defined, after one of theprimary component carriers completes LBT. If the remaining primarycomponent carriers do not complete LBT before the completion of theself-deferral period, only the primary carriers which have completed theLBT process are used for transmission. If the LBT on all primarycarriers is completed before the self-deferral, a CCA check (e.g., 25μs) is performed on all of the component carriers just before completionof the LBT on all of the primary component carriers. After this check,all idle carriers are used for transmission, which includes primarycarriers idle during the LBT period and all carriers idle during the CCAcheck. In the embodiment of FIG. 6, the operations are similar to theoperations of FIG. 5, except that the independent random number isindependent for each primary carrier. Thus, the idle state in operation604 following the configuration in operation 602 leads to transmissiondeterminations in operations and. The independent number generationoccurs in operation 612 using inputs from operation. The system waitsfor an idle primary carrier during the loops of operations 628, 632,636, 634 and 622. After at least one idle primary is identified inoperation, then a self-deferral period taking T microseconds occurs. Atthe end of this period, non-primary channels perform a channel sensingto determine if they are idle. All idle channels determined inoperations 626, 624 and 620 (e.g., the set of channels F) are used fortransmission in operation 614. If additional transmissions are to bemade (operation 610), then the process repeats with an initial deferralor back-off CCA in operation 616. If no additional transmissions are tobe made, all channels return to an idle state.

FIG. 7 then illustrates an example method 700 that operates according toone embodiment. The method 700 is performed by either a UE or an eNBhaving one or more processors and a memory. In various otherembodiments, circuitry of the device may be configured to implementoperations corresponding to the operations of method 700, orinstructions stored in the memory of the device may configure circuitryof the device to perform such operations as the device is configured forlicense-assisted access (LAA) or LTE-U communications between a UE andan eNB.

The illustrated method 700 begins with operation 705 where the device isconfigured to identify one or more LAA (or LTE-U) messages forcommunication on one or more component carriers using one or moreunlicensed channels corresponding to the component carriers.

The system then performs an extended listen before talk operation toallow multiple carriers to transmit at once in an aligned fashion.Transmission may occur with only one carrier, but the operations attemptto identify multiple carriers and to begin transmission on the multiplecarriers at nearly the same time, as illustrated in FIG. 2. To verifythe back-off period, operation 710 involves generation of a first randomnumber associated with a first primary carrier of the one or morecomponent carriers, and then operation 715 involves sensing, during aback-off period based on the first random number, a first channel of theone or more unlicensed channels corresponding to the first primarycarrier. As described above, in systems with multiple primary carriers,the random number may be shared, or each primary carrier may have anindependent back-off counter. When at the first primary carrier reachesthe end of its corresponding back-off period, a self-deferral periodbegins in operation 720 to allow any other channels to achieve an idlestate and align transmissions with the first primary carrier. Inoperation 720, all channels for the system are sensed. This includes anoperation to sense, during the self-deferral period following theback-off period, the first channel. If none of the primary channels areidle, the transmission does not proceed until at least the first primarychannel is idle and available for transmission. At operation 725, adetermination is made, based on the sensing during the back-off periodand the self-deferral period, that the first channel is idle andtherefore available for transmission. In operation 730, the devicetransmits the one or more LAA messages using the first channel based onthe determination that the first channel is idle. If other primarychannels or non-primary channels are identified as idle during theself-deferral period, those channels are also used to transmit the oneor more LAA messages during the same transmission time used to transmiton the first primary channel. The above is one example embodiment of amethod. Various additional embodiments are described below.

Examples

In various embodiments, methods, apparatus, media, computer programproducts, or other implementations may be presented as exampleembodiments in accordance with the descriptions provided above. Certainembodiments may include UEs such as phones, tablets, mobile computers,or other such devices. Some embodiments may be integrated circuitcomponents of such devices, such as circuits implementing MAC and/or L1processing in integrated circuitry. In some embodiments, functionalitymay be on a single chip or multiple chips in an apparatus. Some suchembodiments may further include transmit and receive circuitry onintegrated or separate circuits, with antennas that are similarlyintegrated or separate structures of a device. Any such components orcircuit elements may similarly apply to evolved node B embodimentsdescribed herein.

Example 1 is a computer readable medium comprising instructions that,when executed by one or more processors, configure an evolved node B(eNB) for license-assisted access communications, the instructions toconfigure the eNB to: determine, by the eNB, that a first channel isidle based on a sensing of the first channel for a first period of time;initiate, based on the determination that the first channel is idle, areservation signal on the first channel for a second period of timefollowing the first period of time; initiate transmission of an uplinkgrant to a first user equipment (UE), the uplink grant associated withthe first channel and a third period of time following the second periodof time; and sense, by the eNB, the first channel during the thirdperiod of time to detect a physical uplink shared channel (PUSCH)transmission associated with the uplink grant.

In Example 2, the subject matter of Example 1 optionally includeswherein the second period of time is separated from the third period oftime by a UE sensing period such that the first UE senses the firstchannel during the UE sensing period following transmission of thereservation signal to determine that the first channel is idle duringthe UE sensing period.

In Example 3, the subject matter of any one or more of Examples 1optionally includes wherein the third period of time immediately followsthe second period of time; and wherein the UE is configured tocommunicate the PUSCH transmission on the first channel during the thirdperiod of time without performing a listen-before-talk (LBT) operation.

In Example 4, the subject matter of any one or more of Examples 1-3optionally includes wherein the uplink grant is communicated from theeNB to the first UE on a second channel different from the first channelas part of a physical downlink control channel (PDCCH) transmission.

In Example 5, the subject matter of any one or more of Examples 1-4optionally includes wherein the reservation signal comprises one or moreof a PDCCH, a physical downlink shared channel (PDSCH), and ademodulation reference signal (DRS).

In Example 6, the subject matter of any one or more of Examples 1-5optionally includes where the reservation signal comprises a primarysynchronization signal (PSS) and a secondary synchronization signal(SSS).

In Example 7, the subject matter of any one or more of Examples 1-6optionally includes wherein the instructions further configure the eNBto: receive a plurality of scheduling requests from a plurality of UEs,the plurality of UEs comprising the first UE; and wherein initiatingtransmission of the uplink grant to the first UE comprises initiatingtransmission of the uplink grant to each UE of the plurality of UEs.

In Example 8, the subject matter of Example 7 optionally includeswherein the instructions further configure the eNB to assign a firstlicense-assisted access radio network temporary identifier to each UE ofthe plurality of UEs, wherein the license-assisted access radio networktemporary identifier is separate from a cell radio network temporaryidentifier (C-RNTI) for each UE of the plurality of UEs; and wherein thetransmission of the uplink grant to each UE of the plurality of UEs usesthe first license-assisted access radio network temporary identifiersuch that the plurality of UEs receives the uplink grant using a sameidentifier.

In Example 9, the subject matter of examples 1-8 above includesembodiments wherein each UE of the plurality of UEs performs an LBToperation after receiving the uplink grant; and wherein the first UEcompletes a successful carrier sensing operation and reserves the firstchannel with a second reservation signal prior to each other UE of theplurality of UEs. Such embodiments can operate wherein the secondreservation signal comprises a first C-RNTI for the first UE.

In Example 10, the subject matter of any one or more of Examples 1-9optionally includes wherein the instructions further configure the eNBto: successfully decode the PUSCH transmission associated with theuplink grant; and transmit a synchronous hybrid automatic repeat requestassociated with the PUSCH transmission to the first UE.

In Example 11, the subject matter of any one or more of Examples 1-10optionally includes wherein the instructions further configure the eNBto: determine that the eNB has failed to identify the PUSCH transmissionon the first channel during the third period of time; and transmit anasynchronous hybrid automatic repeat request from the eNB to the firstUE in response to the failure to identify the PUSCH transmission.

In Example 12, the subject matter of Example 11 optionally includeswherein the uplink grant comprises a transmission grant associated withthe third period of time and a retransmission grant associated with afourth period of time following the second period of time.

In Example 13, the subject matter of Example 12 optionally includeswherein a number of physical resource blocks for the uplink grant areadjusted dynamically by the eNB between the third period of time and thefourth period of time.

In Example 14, the subject matter of any one or more of Examples 12-13optionally includes wherein a modulation and coding scheme associatedwith the uplink grant is set dynamically by the eNB based on the sensingof the first channel for the first period of time and the failure toidentify the PUSCH transmission.

Example 15 is an apparatus of an evolved node B (eNB) comprising controlcircuitry configured to: determine that a first channel is idle based ona sensing of the first channel for a first period of time; initiate,based on the determination that the first channel is idle, a reservationsignal on the first channel for a second period of time following thefirst period of time; initiate transmission of an uplink grant to afirst user equipment (UE), the uplink grant associated with the firstchannel and a third period of time following the second period of time;initiate sensing of the first channel during the third period of time todetect a PUSCH transmission associated with the uplink grant; andgenerate a hybrid automatic repeat request for transmission to the firstUE in response to the sensing of the first channel.

In Example 16, the subject matter of Example 15 optionally includesfurther comprising: receive circuitry coupled to the control circuitryand configured to sense the first channel during the first period oftime and the second period of time and to receive the PUSCHtransmission; and transmit circuitry coupled to the control circuitryand configured to transmit the reservation signal to the first UE on thefirst channel.

In Example 17, the subject matter of any one or more of Examples 15-16optionally includes wherein the receive circuitry and the transmitcircuitry are coupled to a first antenna; wherein the first antenna isconfigured for communications on the first channel comprising anunlicensed channel; and wherein the first antenna is further configuredfor communications on a second channel comprising a licensed channel.

Example 18 is a computer readable medium comprising instructions that,when executed by one or more processors, configure a user equipment (UE)for license-assisted access communication with an evolved node B (eNB),the instructions to configure the UE to: receive, from the eNB, anuplink grant associated with a first unlicensed channel and a firstperiod of time; determine that the first unlicensed channel is availablefor a PUSCH transmission during the first period of time; transmit thePUSCH transmission to the eNB during the first period of time; andreceive a hybrid automatic repeat request associated with the PUSCHtransmission from the eNB.

In Example 19, the subject matter of Example 18 optionally includeswherein the UE determines that the first unlicensed channel is availablefor the PUSCH transmission based on receipt of a reservation signaltransmitted from the eNB.

In Example 20, the subject matter of any one or more of Examples 18-19optionally includes wherein the UE determines that the first unlicensedchannel is available for the PUSCH transmission based on a listen beforetalk operation performed by the UE.

Example 21 is an apparatus of a user equipment (UE) configured forlicense-assisted access communications with an evolved node B (eNB), theUE comprising: receive circuitry configured to receive, from the eNB, anuplink grant associated with a first unlicensed channel for a PUSCHtransmission, and to receive an asynchronous hybrid automatic repeatrequest associated with the PUSCH transmission; control circuitryconfigured to determine that the first unlicensed channel is availablefor the PUSCH transmission; and transmit circuitry configured totransmit the PUSCH transmission to the eNB in response to the controlcircuitry determining that the first unlicensed channel is available forthe PUSCH transmission.

In Example 22, the subject matter of Example 21 optionally includeswherein the control circuitry is configured to determine that the firstunlicensed channel is available for the PUSCH transmission by: decodingthe uplink grant to identify a first license-assisted access radionetwork temporary identifier associated with a plurality of UEs;processing carrier sensing data from the receive circuitry to determinethat the first unlicensed channel meets a set of availability criteriaand that each other UE of the plurality of UEs has not sent a priorreservation signal; and initiating transmission, using the transmitcircuitry, of a first UE reservation signal, the first UE reservationsignal comprising a first C-RNTI for the UE.

Example 23 is a method of uplink scheduling for wireless communicationsystems, comprising: an eNB and UEs capable of performinglisten-before-talk (LBT) with extended CCA mechanism, wherein i) the eNBand UEs can sense a channel to determine if the channel is busy or idle,and transmit after a random duration specified within a given interval;and ii) the eNB and UEs can reserve the channel for a specific durationby sending data, reference signals, or any other known possible signal.

Example 24 is the method of example 23 wherein the eNB can schedule theUEs using an existing PDCCH mechanism and allocate resources for anuplink subframe in unlicensed bands.

Example 25 is the method of examples 23-24 wherein the eNB senses thechannel, reserves the channel with a reservation signal, and transmitsuplink grants to the UEs, and the UEs transmit PUSCH on the scheduledsubframe without sensing the channel.

Example 26 is the method of examples 23-24 wherein the eNB senses thechannel, reserves the channel with a reservation signal, and transmitsuplink grants to the UEs, and the UEs transmit PUSCH on the scheduledsubframe after sensing the channel. If the channel is not idle, the UEsdo not transmit.

Example 27 is the method of examples 23-26, wherein uplink grants aretransmitted to the UEs on licensed bands via cross-carrier scheduling(without sensing the channel), and the UEs transmit PUSCH on thescheduled subframe only when the channel is sensed idle.

Example 28 is the method of examples 23-27 wherein the reservationsignal can be DL transmissions, e.g., (e)PDCCH, PDSCH, DRS, and PSS/SSS.

Example 29 is the method of examples 23-28 wherein the eNB should nottransmit anything on an unlicensed carrier for a certain time durationduring which a scheduled UE can sense the channel.

Example 30 is the method of examples 23-29 wherein a new DCI can bedefined for scheduling multiple subframes for a UE with a single uplinkgrant. The DCI format can include C-RNTI of the UE and a number ofmaximum subframes the UE is allowed to transmit.

Example 31 is the method of examples 23-30 wherein the eNB may send anuplink grant for a specific subframe to a group of UEs which requestedscheduling.

Example 32 is the method of examples 23-31 wherein a new RNTI can bedefined and used by the eNB instead of C-RNTI when a cyclic redundancycheck (CRC) is attached to a DCI message payload, so that a group of UEsassigned the same value can receive PDCCH.

Example 33 is the method of examples 23-32 wherein upon receiving anuplink grant from the eNB, the group of UEs performs LBT. The first UEwith successful carrier sensing can reserve the channel with areservation signal until the start of the scheduled subframe and thentransmit data on PUSCH.

Example 34 is the method of examples 23-33 wherein the reservationsignal can include the UE's C-RNTI, modulation coding scheme (MCS), etc.

Example 35 is the method of examples 23-34 wherein both the eNB and theUE perform LBT independently with their own LBT parameters.

Example 36 is the method, medium, or device of any embodiment abovewherein flexible asynchronous hybrid automatic repeat request (HARQ).operation is used.

Example 37 is the method, device, or medium of any embodiment abovewherein the eNB can send an uplink grant for each uplink transmission(including initial transmission and retransmission) in unlicensed bandsfor asynchronous HARQ operation.

Example 38 is the method of any embodiment above wherein the eNB candynamically change parameters, e.g., the number of physical resourceblocks (PRBs) and MCS.

Example 39 is the method of any embodiment above wherein the eNBperforms a blind detection, for instance, an energy detection or anyform of detection, for the scheduled PUSCH resources.

In any of the embodiments, above, the system may operate using componentcarriers in a licensed spectrum along with the one or more componentcarriers in an unlicensed spectrum. Other embodiments may operate usingonly unlicensed component carriers.

Example 40 is the method of any embodiment above involving communicationof a portion of the one or more LAA messages between the eNB and UEusing one or more licensed channels along and during the same timeperiod as the use of the unlicensed channels.

Example 41 is the method of any embodiment above wherein the one or moreLAA message are communicated between a UE and an eNB using onlyunlicensed channels without a licensed channel used to manage LBT on theone or more unlicensed channels.

Further, in various embodiments using feedback systems, contentionwindows defining the allowable range for random numbers for each channelmay either be set together, or separately for each unlicensed channel,or for each primary unlicensed channel.

Example 42 is a user equipment (UE) configured for multi-carrieroperation for license-assisted access (LAA) with an evolved node B(eNB), the UE comprising baseband circuitry configured to: identify oneor more LAA messages for communication on one or more component carriersusing one or more unlicensed channels corresponding to the componentcarriers; access a negative acknowledgement history associated with theone or more unlicensed channels; adjust a first contention window baseon the negative acknowledgement history; generate a first random numberassociated with a first primary carrier of the one or more componentcarriers using the contention window; sense, during a back-off periodbased on the first random number, a first channel of the one or moreunlicensed channels corresponding to the first primary carrier; sense,during a self-deferral period following the back-off period, the firstchannel; determine, based on the sensing during the back-off period andthe self-deferral period, that the first channel is idle; and initiatetransmission of the one or more LAA messages using the first channelbased on the determination that the first channel is idle.

Example 43 is an embodiment of example 42 further comprising applicationcircuitry configured to generate the one or more LAA messages.

Example 44 is an embodiment of examples 42-43 wherein the firstcontention window defines allowable back-off periods for a plurality ofunlicensed channels.

Example 43 is an embodiment of examples 42-43 UE of claims 25-26 whereinthe baseband circuitry is further configured to: adjust a secondcontention window base on a second portion negative acknowledgementhistory; wherein the first contention window is set only for a firstunlicensed channel based on a first portion of the negativeacknowledgement history for negative acknowledgements on the firstunlicensed channel; and wherein the second contention window differentfrom the first contention window is set for a second unlicensed channelbased on the second portion of the negative acknowledgement history forthe second unlicensed channel.

Further, in addition to the specific combinations of examples describedabove, any of the examples detailing further implementations of anelement of an apparatus or medium may be applied to any othercorresponding apparatus or medium, or may be implemented in conjunctionwith another apparatus or medium. Thus, each example above may becombined with each other example in various ways both as implementationsin a system and as combinations of elements to generate an embodimentfrom the combination of each example or group of examples. For example,any embodiment above describing a transmitting device will have anembodiment that receives the transmission, even if such an embodiment isnot specifically detailed. Similarly, methods, apparatus examples, andcomputer readable medium examples may each have a corresponding exampleof the other type even if such examples for every embodiment are notspecifically detailed.

Example Systems and Devices

FIG. 8 illustrates aspects of a computing machine according to someexample embodiments. Embodiments described herein may be implementedinto a system 800 using any suitably configured hardware and/orsoftware. FIG. 8 illustrates, for some embodiments, an example system800 comprising radio frequency (RF) circuitry 835, baseband circuitry830, application circuitry 825, memory/storage 840, a display 805, acamera 820, a sensor 815, and an input/output (I/O) interface 810,coupled with each other at least as shown.

The application circuitry 825 may include circuitry such as, but notlimited to, one or more single-core or multi-core processors. Theprocessor(s) may include any combination of general-purpose processorsand dedicated processors (e.g., graphics processors, applicationprocessors, etc.). The processors may be coupled with the memory/storage840 and configured to execute instructions stored in the memory/storage840 to enable various applications and/or operating systems running onthe system 800.

The baseband circuitry 830 may include circuitry such as, but notlimited to, one or more single-core or multi-core processors. Theprocessor(s) may include a baseband processor. The baseband circuitry830 may handle various radio control functions that enable communicationwith one or more radio networks via the RF circuitry 835. The radiocontrol functions may include, but are not limited to, signalmodulation, encoding, decoding, radio frequency shifting, and the like.In some embodiments, the baseband circuitry 830 may provide forcommunication compatible with one or more radio technologies. Forexample, in some embodiments, the baseband circuitry 830 may supportcommunication with an evolved universal terrestrial radio access network(EUTRAN), other wireless metropolitan area networks (WMANs), a wirelesslocal area network (WLAN), or a wireless personal area network (WPAN).Embodiments in which the baseband circuitry 830 is configured to supportradio communications of more than one wireless protocol may be referredto as multi-mode baseband circuitry.

In various embodiments, the baseband circuitry 830 may include circuitryto operate with signals that are not strictly considered as being in abaseband frequency. For example, in some embodiments, the basebandcircuitry 830 may include circuitry to operate with signals having anintermediate frequency, which is between a baseband frequency and aradio frequency.

The RF circuitry 835 may enable communication with wireless networksusing modulated electromagnetic radiation through a non-solid medium. Invarious embodiments, the RF circuitry 835 may include switches, filters,amplifiers, and the like to facilitate the communication with thewireless network.

In various embodiments, the RF circuitry 835 may include circuitry tooperate with signals that are not strictly considered as being in aradio frequency. For example, in some embodiments, the RF circuitry 835may include circuitry to operate with signals having an intermediatefrequency, which is between a baseband frequency and a radio frequency.

In various embodiments, the transmitter circuitry or receiver circuitrydiscussed above with respect to the UE 101 or the eNB 150 may beembodied in whole or in part in one or more of the RF circuitry 835, thebaseband circuitry 830, and/or the application circuitry 825.

In some embodiments, some or all of the constituent components of abaseband processor may be used to implement aspects of any embodimentdescribed herein. Such embodiments may be implemented by the basebandcircuitry 830, the application circuitry 825, and/or the memory/storage840 implemented together on a system on a chip (SOC).

The memory/storage 840 may be used to load and store data and/orinstructions, for example, for the system 800. The memory/storage 840,in one embodiment, may include any combination of suitable volatilememory (e.g., dynamic random access memory (DRAM)) and/or non-volatilememory (e.g., flash memory).

In various embodiments, the I/O interface 810 may include one or moreuser interfaces designed to enable user interaction with the system 800and/or peripheral component interfaces designed to enable peripheralcomponent interaction with the system 800. User interfaces may include,but are not limited to, a physical keyboard or keypad, a touchpad, aspeaker, a microphone, and so forth. Peripheral component interfaces mayinclude, but are not limited to, a non-volatile memory port, a universalserial bus (USB) port, an audio jack, and a power supply interface.

In various embodiments, the sensor 815 may include one or more sensingdevices to determine environmental conditions and/or locationinformation related to the system 800. In some embodiments, the sensors815 may include, but are not limited to, a gyro sensor, anaccelerometer, a proximity sensor, an ambient light sensor, and apositioning unit. The positioning unit may also be part of, or interactwith, the baseband circuitry 830 and/or RF circuitry 835 to communicatewith components of a positioning network (e.g., a global positioningsystem (GPS) satellite). In various embodiments, the display 805 mayinclude a display (e.g., a liquid crystal display, a touch screendisplay, etc.).

In various embodiments, the system 800 may be a mobile computing devicesuch as, but not limited to, a laptop computing device, a tabletcomputing device, a netbook, an ultrabook, a smartphone, and the like.In various embodiments, the system 800 may have more or fewercomponents, and/or different architectures.

FIG. 9 shows an example UE, illustrated as a UE 900. The UE 900 may bean implementation of the UE 101, or any device described herein. The UE900 can include one or more antennas 908 configured to communicate witha transmission station, such as a base station (BS), an eNB, or anothertype of wireless wide area network (WWAN) access point. The UE 900 canbe configured to communicate using at least one wireless communicationstandard including 3GPP LTE, WiMAX, High Speed Packet Access (HSPA),Bluetooth, and WiFi. The UE 900 can communicate using separate antennasfor each wireless communication standard or shared antennas for multiplewireless communication standards. The UE 900 can communicate in a WLAN,a WPAN, and/or a WWAN.

FIG. 9 also shows a microphone 920 and one or more speakers 912 that canbe used for audio input and output to and from the UE 900. A displayscreen 904 can be a liquid crystal display (LCD) screen, or another typeof display screen such as an organic light emitting diode (OLED)display. The display screen 904 can be configured as a touch screen. Thetouch screen can use capacitive, resistive, or another type of touchscreen technology. An application processor 914 and a graphics processor918 can be coupled to an internal memory 916 to provide processing anddisplay capabilities. A non-volatile memory port 910 can also be used toprovide data I/O options to a user. The non-volatile memory port 910 canalso be used to expand the memory capabilities of the UE 900. A keyboard906 can be integrated with the UE 900 or wirelessly connected to the UE900 to provide additional user input. A virtual keyboard can also beprovided using the touch screen. A camera 922 located on the front(display screen) side or the rear side of the UE 900 can also beintegrated into a housing 902 of the UE 900.

FIG. 10 is a block diagram illustrating an example computer systemmachine 1000 upon which any one or more of the methodologies hereindiscussed can be run, and which may be used to implement the eNB 150,the UE 101, or any other device described herein. In various alternativeembodiments, the machine operates as a standalone device or can beconnected (e.g., networked) to other machines. In a networkeddeployment, the machine can operate in the capacity of either a serveror a client machine in server-client network environments, or it can actas a peer machine in peer-to-peer (or distributed) network environments.The machine can be a personal computer (PC) that may or may not beportable (e.g., a notebook or a netbook), a tablet, a set-top box (STB),a gaming console, a Personal Digital Assistant (PDA), a mobile telephoneor smartphone, a web appliance, a network router, switch, or bridge, orany machine capable of executing instructions (sequential or otherwise)that specify actions to be taken by that machine. Further, while only asingle machine is illustrated, the term “machine” shall also be taken toinclude any collection of machines that individually or jointly executea set (or multiple sets) of instructions to perform any one or more ofthe methodologies discussed herein.

The example computer system machine 1000 includes a processor 1002(e.g., a central processing unit (CPU), a graphics processing unit(GPU), or both), a main memory 1004, and a static memory 1006, whichcommunicate with each other via an interconnect 1008 (e.g., a link, abus, etc.). The computer system machine 1000 can further include a videodisplay device 1010, an alphanumeric input device 1012 (e.g., akeyboard), and a user interface (UI) navigation device 1014 (e.g., amouse). In one embodiment, the video display unit 1010, alphanumericinput device 1012, and UI navigation device 1014 are a touch screendisplay. The computer system machine 1000 can additionally include amass storage device 1016 (e.g., a drive unit), a signal generationdevice 1018 (e.g., a speaker), an output controller 1032, a powermanagement controller 1034, a network interface device 1020 (which caninclude or operably communicate with one or more antennas 1030,transceivers, or other wireless communications hardware), and one ormore sensors 1028, such as a GPS sensor, compass, location sensor,accelerometer, or other sensor.

The mass storage device 1016 includes a machine-readable medium 1022 onwhich is stored one or more sets of data structures and instructions1024 (e.g., software) embodying or utilized by any one or more of themethodologies or functions described herein. The instructions 1024 canalso reside, completely or at least partially, within the main memory1004, static memory 1006, and/or processor 1002 during execution thereofby the computer system machine 1000, with the main memory 1004, thestatic memory 1006, and the processor 1002 also constitutingmachine-readable media.

While the machine-readable medium 1022 is illustrated in an exampleembodiment to be a single medium, the term “machine-readable medium” caninclude a single medium or multiple media (e.g., a centralized ordistributed database, and/or associated caches and servers) that storethe one or more instructions 1024. The term “machine-readable medium”shall also be taken to include any tangible medium that is capable ofstoring, encoding, or carrying instructions for execution by the machineand that cause the machine to perform any one or more of themethodologies of the present disclosure, or that is capable of storing,encoding, or carrying data structures utilized by or associated withsuch instructions.

The instructions 1024 can further be transmitted or received over acommunications network 1026 using a transmission medium via the networkinterface device 1020 utilizing any one of a number of well-knowntransfer protocols (e.g., hypertext transfer protocol (HTTP)). The term“transmission medium” shall be taken to include any medium that iscapable of storing, encoding, or carrying instructions for execution bythe machine, and includes digital or analog communications signals orother intangible media to facilitate communication of such software.

Various techniques, or certain aspects or portions thereof, may take theform of program code (i.e., instructions) embodied in tangible media,such as floppy diskettes, CD-ROMs, hard drives, computer readablestorage media, or any other machine-readable storage medium wherein,when the program code is loaded into and executed by a machine, such asa computer, the machine becomes an apparatus for practicing the varioustechniques. In the case of program code execution on programmablecomputers, the computing device may include a processor, a storagemedium readable by the processor (including volatile and non-volatilememory and/or storage elements), at least one input device, and at leastone output device. The volatile and non-volatile memory and/or storageelements may be a RAM, Erasable Programmable Read-Only Memory (EPROM),flash drive, optical drive, magnetic hard drive, or other medium forstoring electronic data. The base station and mobile station or eNB andUE may also include a transceiver module, a counter module, a processingmodule, and/or a clock module or timer module. One or more programs thatmay implement or utilize the various techniques described herein may usean application programming interface (API), reusable controls, and thelike. Such programs may be implemented in a high level procedural orobject-oriented programming language to communicate with a computersystem. However, the program(s) may be implemented in assembly ormachine language, if desired. In any case, the language may be acompiled or interpreted language, and combined with hardwareimplementations.

Various embodiments may use 3GPP LTE/LTE-A, Institute of Electrical andElectronic Engineers (IEEE) 1002.11, and Bluetooth communicationstandards. Various alternative embodiments may use a variety of otherWWAN, WLAN, and WPAN protocols and standards in connection with thetechniques described herein. These standards include, but are notlimited to, other standards from 3GPP (e.g., HSPA+, UMTS), IEEE 1002.16(e.g., 1002.16p), or Bluetooth (e.g., Bluetooth 9.0, or like standardsdefined by the Bluetooth Special Interest Group) standards families.Other applicable network configurations can be included within the scopeof the presently described communication networks. It will be understoodthat communications on such communication networks can be facilitatedusing any number of PANs, LANs, and WANs, using any combination of wiredor wireless transmission mediums.

FIG. 11 illustrates, for one embodiment, example components of a UE 1100in accordance with some embodiments. In some embodiments, the UE 1100may include application circuitry 1102, baseband circuitry 1104, RadioFrequency (RF) circuitry 1106, front-end module (FEM) circuitry 1108,and one or more antennas 1110, coupled together at least as shown. Insome embodiments, the UE 1100 may include additional elements such as,for example, memory/storage, a display, a camera, a sensor, and/or aninput/output (I/O) interface.

The application circuitry 1102 may include one or more applicationprocessors. For example, the application circuitry 1102 may includecircuitry such as, but not limited to, one or more single-core ormulti-core processors. The processor(s) may include any combination ofgeneral-purpose processors and dedicated processors (e.g., graphicsprocessors, application processors, etc.). The processors may be coupledwith and/or may include memory/storage and may be configured to executeinstructions stored in the memory/storage to enable various applicationsand/or operating systems to run on the UE 1100.

The baseband circuitry 1104 may include circuitry such as, but notlimited to, one or more single-core or multi-core processors. Thebaseband circuitry 1104 may include one or more baseband processorsand/or control logic to process baseband signals received from a receivesignal path of the RF circuitry 1106 and to generate baseband signalsfor a transmit signal path of the RF circuitry 1106. The basebandcircuitry 1104 may interface with the application circuitry 1102 forgeneration and processing of the baseband signals and for controllingoperations of the RF circuitry 1106. For example, in some embodiments,the baseband circuitry 1104 may include a second generation (2G)baseband processor 1104 a, third generation (3G) baseband processor 1104b, fourth generation (4G) baseband processor 1104 c, and/or otherbaseband processor(s) 1104 d for other existing generations, generationsin development, or generations to be developed in the future (e.g.,fifth generation (5G), 6G, etc.). The baseband circuitry 1104 (e.g., oneor more of the baseband processors 1104 a-d) may handle various radiocontrol functions that enable communication with one or more radionetworks via the RF circuitry 1106. The radio control functions mayinclude, but are not limited to, signal modulation/demodulation,encoding/decoding, radio frequency shifting, etc. In some embodiments,modulation/demodulation circuitry of the baseband circuitry 1104 mayinclude Fast-Fourier Transform (FFT), precoding, and/or constellationmapping/demapping functionality. In some embodiments, encoding/decodingcircuitry of the baseband circuitry 1104 may include convolution,tail-biting convolution, turbo, Viterbi, and/or Low Density Parity Check(LDPC) encoder/decoder functionality. Embodiments ofmodulation/demodulation and encoder/decoder functionality are notlimited to these examples and may include other suitable functionalityin other embodiments.

In some embodiments, the baseband circuitry 1104 may include elements ofa protocol stack such as, for example, elements of an EUTRAN protocolincluding, for example, physical (PHY), media access control (MAC),radio link control (RLC), packet data convergence protocol (PDCP),and/or RRC elements. A central processing unit (CPU) 1104 e of thebaseband circuitry 1104 may be configured to run elements of theprotocol stack for signaling of the PHY, MAC, RLC, PDCP, and/or RRClayers. In some embodiments, the baseband circuitry 1104 may include oneor more audio digital signal processor(s) (DSP) 1104 f The audio DSP(s)1104 f may include elements for compression/decompression and echocancellation and may include other suitable processing elements in otherembodiments. Components of the baseband circuitry 1104 may be suitablycombined in a single chip or a single chipset, or disposed on a samecircuit board in some embodiments. In some embodiments, some or all ofthe constituent components of the baseband circuitry 1104 and theapplication circuitry 1102 may be implemented together, such as, forexample, on a system on a chip (SOC).

In some embodiments, the baseband circuitry 1104 may provide forcommunication compatible with one or more radio technologies. Forexample, in some embodiments, the baseband circuitry 1104 may supportcommunication with an EUTRAN and/or a WMAN, a WLAN, or a WPAN.Embodiments in which the baseband circuitry 1104 is configured tosupport radio communications of more than one wireless protocol may bereferred to as multi-mode baseband circuitry.

The RF circuitry 1106 may enable communication with wireless networksusing modulated electromagnetic radiation through a non-solid medium. Invarious embodiments, the RF circuitry 1106 may include switches,filters, amplifiers, et cetera to facilitate the communication with thewireless network. The RF circuitry 1106 may include a receive signalpath which may include circuitry to down-convert RF signals receivedfrom the FEM circuitry 1108 and provide baseband signals to the basebandcircuitry 1104. The RF circuitry 1106 may also include a transmit signalpath which may include circuitry to up-convert baseband signals providedby the baseband circuitry 1104 and provide RF output signals to the FEMcircuitry 1108 for transmission.

In some embodiments, the RF circuitry 1106 may include a receive signalpath and a transmit signal path. The receive signal path of the RFcircuitry 1106 may include mixer circuitry 1106 a, amplifier circuitry1106 b, and filter circuitry 1106 c. The transmit signal path of the RFcircuitry 1106 may include the filter circuitry 1106 c and the mixercircuitry 1106 a. The RF circuitry 1106 may also include synthesizercircuitry 1106 d for synthesizing a frequency for use by the mixercircuitry 1106 a of the receive signal path and the transmit signalpath. In some embodiments, the mixer circuitry 1106 a of the receivesignal path may be configured to down-convert RF signals received fromthe FEM circuitry 1108 based on the synthesized frequency provided bythe synthesizer circuitry 1106 d. The amplifier circuitry 1106 b may beconfigured to amplify the down-converted signals, and the filtercircuitry 1106 c may be a low-pass filter (LPF) or band-pass filter(BPF) configured to remove unwanted signals from the down-convertedsignals to generate output baseband signals. Output baseband signals maybe provided to the baseband circuitry 1104 for further processing. Insome embodiments, the output baseband signals may be zero-frequencybaseband signals, although this is not a requirement. In someembodiments, the mixer circuitry 1106 a of the receive signal path maycomprise passive mixers, although the scope of the embodiments is notlimited in this respect.

In some embodiments, the mixer circuitry 1106 a of the transmit signalpath may be configured to up-convert input baseband signals based on thesynthesized frequency provided by the synthesizer circuitry 1106 d togenerate RF output signals for the FEM circuitry 1108. The basebandsignals may be provided by the baseband circuitry 1104 and may befiltered by the filter circuitry 1106 c. The filter circuitry 1106 c mayinclude an LPF, although the scope of the embodiments is not limited inthis respect.

In some embodiments, the mixer circuitry 1106 a of the receive signalpath and the mixer circuitry 1106 a of the transmit signal path mayinclude two or more mixers and may be arranged for quadrature downconversion and/or up conversion respectively. In some embodiments, themixer circuitry 1106 a of the receive signal path and the mixercircuitry 1106 a of the transmit signal path may include two or moremixers and may be arranged for image rejection (e.g., Hartley imagerejection). In some embodiments, the mixer circuitry 1106 a of thereceive signal path and the mixer circuitry 1106 a of the transmitsignal path may be arranged for direct down conversion and/or direct upconversion, respectively. In some embodiments, the mixer circuitry 1106a of the receive signal path and the mixer circuitry 1106 a of thetransmit signal path may be configured for super-heterodyne operation.

In some embodiments, the output baseband signals and the input basebandsignals may be analog baseband signals, although the scope of theembodiments is not limited in this respect. In some alternateembodiments, the output baseband signals and the input baseband signalsmay be digital baseband signals. In these alternate embodiments, the RFcircuitry 1106 may include analog-to-digital converter (ADC) anddigital-to-analog converter (DAC) circuitry and the baseband circuitry1104 may include a digital baseband interface to communicate with the RFcircuitry 1106.

In some dual-mode embodiments, a separate radio IC circuitry may beprovided for processing signals for each spectrum, although the scope ofthe embodiments is not limited in this respect.

In some embodiments, the synthesizer circuitry 1106 d may be afractional-N synthesizer or a fractional N/N+1 synthesizer, although thescope of the embodiments is not limited in this respect, as other typesof frequency synthesizers may be suitable. For example, the synthesizercircuitry 1106 d may be a delta-sigma synthesizer, a frequencymultiplier, or a synthesizer comprising a phase-locked loop with afrequency divider.

The synthesizer circuitry 1106 d may be configured to synthesize anoutput frequency for use by the mixer circuitry 1106 a of the RFcircuitry 1106 based on a frequency input and a divider control input.In some embodiments, the synthesizer circuitry 1106 d may be afractional N/N+1 synthesizer.

In some embodiments, frequency input may be provided by a voltagecontrolled oscillator (VCO), although that is not a requirement. Dividercontrol input may be provided by either the baseband circuitry 1104 orthe application circuitry 1102 depending on the desired outputfrequency. In some embodiments, a divider control input (e.g., N) may bedetermined from a look-up table based on a channel indicated by theapplication circuitry 1102.

The synthesizer circuitry 1106 d of the RF circuitry 1106 may include adivider, a delay-locked loop (DLL), a multiplexer, and a phaseaccumulator. In some embodiments, the divider may be a dual modulusdivider (DMD) and the phase accumulator may be a digital phaseaccumulator (DPA). In some embodiments, the DMD may be configured todivide the input signal by either N or N+1 (e.g., based on a carry out)to provide a fractional division ratio. In some example embodiments, theDLL may include a set of cascaded, tunable delay elements, a phasedetector, a charge pump, and a D-type flip-flop. In these embodiments,the delay elements may be configured to break a VCO period up into Ndequal packets of phase, where Nd is the number of delay elements in thedelay line. In this way, the DLL provides negative feedback to helpensure that the total delay through the delay line is one VCO cycle.

In some embodiments, the synthesizer circuitry 1106 d may be configuredto generate a carrier frequency as the output frequency, while in otherembodiments, the output frequency may be a multiple of the carrierfrequency (e.g., twice the carrier frequency, four times the carrierfrequency) and used in conjunction with quadrature generator and dividercircuitry to generate multiple signals at the carrier frequency withmultiple different phases with respect to each other. In someembodiments, the output frequency may be a LO frequency (fLO). In someembodiments, the RF circuitry 1106 may include an IQ/polar converter.

The FEM circuitry 1108 may include a receive signal path which mayinclude circuitry configured to operate on RF signals received from theone or more antennas 1110, amplify the received signals, and provide theamplified versions of the received signals to the RF circuitry 1106 forfurther processing. The FEM circuitry 1108 may also include a transmitsignal path which may include circuitry configured to amplify signalsfor transmission provided by the RF circuitry 1106 for transmission byone or more of the one or more antennas 1110.

In some embodiments, the FEM circuitry 1108 may include a TX/RX switchto switch between transmit mode and receive mode operation. The FEMcircuitry 1108 may include a receive signal path and a transmit signalpath. The receive signal path of the FEM circuitry 1108 may include alow-noise amplifier (LNA) to amplify received RF signals and provide theamplified received RF signals as an output (e.g., to the RF circuitry1106). The transmit signal path of the FEM circuitry 1108 may include apower amplifier (PA) to amplify input RF signals (e.g., provided by theRF circuitry 1106), and one or more filters to generate RF signals forsubsequent transmission (e.g., by one or more of the one or moreantennas 1110).

In some embodiments, the UE 1100 comprises a plurality of power savingmechanisms. If the UE 1100 is in an RRC Connected state, where it isstill connected to the eNB as it expects to receive traffic shortly,then it may enter a state known as Discontinuous Reception Mode (DRX)after a period of inactivity. During this state, the UE 1100 may powerdown for brief intervals of time and thus save power.

If there is no data traffic activity for an extended period of time,then the UE 1100 may transition to an RRC Idle state, where itdisconnects from the network and does not perform operations such aschannel quality feedback, handover, etc. The UE 1100 goes into a verylow-power state and performs paging, wherein it periodically wakes up tolisten to the network and then powers down again. The UE 1100 cannotreceive data in this state, and in order to receive data, it transitionsback to the RRC Connected state.

An additional power saving mode may allow a device to be unavailable tothe network for periods longer than a paging interval (ranging fromseconds to a few hours). During this time, the device is totallyunreachable to the network and may power down completely. Any data sentduring this time incurs a large delay, and it is assumed that the delayis acceptable.

The embodiments described above can be implemented in one or acombination of hardware, firmware, and software. Various methods ortechniques, or certain aspects or portions thereof, can take the form ofprogram code (i.e., instructions) embodied in tangible media, such asflash memory, hard drives, portable storage devices, read-only memory(ROM), RAM, semiconductor memory devices (e.g., EPROM, ElectricallyErasable Programmable Read-Only Memory (EEPROM)), magnetic disk storagemedia, optical storage media, and any other machine-readable storagemedium or storage device wherein, when the program code is loaded intoand executed by a machine, such as a computer or networking device, themachine becomes an apparatus for practicing the various techniques.

It should be understood that the functional units or capabilitiesdescribed in this specification may have been referred to or labeled ascomponents or modules in order to more particularly emphasize theirimplementation independence. For example, a component or module can beimplemented as a hardware circuit comprising custom very-large-scaleintegration (VLSI) circuits or gate arrays, off-the-shelf semiconductorssuch as logic chips, transistors, or other discrete components. Acomponent or module can also be implemented in programmable hardwaredevices such as field programmable gate arrays, programmable arraylogic, programmable logic devices, or the like. Components or modulescan also be implemented in software for execution by various types ofprocessors. An identified component or module of executable code can,for instance, comprise one or more physical or logical blocks ofcomputer instructions, which can, for instance, be organized as anobject, procedure, or function. Nevertheless, the executables of anidentified component or module need not be physically located together,but can comprise disparate instructions stored in different locationswhich, when joined logically together, comprise the component or moduleand achieve the stated purpose for the component or module.

Indeed, a component or module of executable code can be a singleinstruction, or many instructions, and can even be distributed overseveral different code segments, among different programs, and acrossseveral memory devices. Similarly, operational data can be identifiedand illustrated herein within components or modules, and can be embodiedin any suitable form and organized within any suitable type of datastructure. The operational data can be collected as a single data set,or can be distributed over different locations including over differentstorage devices, and can exist, at least partially, merely as electronicsignals on a system or network. The components or modules can be passiveor active, including agents operable to perform desired functions.

What is claimed is:
 1. An apparatus of an evolved node B (eNB), the eNBconfigured for Licensed Assisted Access (LAA) secondary cell (Scell)transmissions on multiple carriers, the apparatus comprising: processingcircuitry; and memory, wherein the processing circuitry is configuredto: perform a channel access procedure on each carrier of a plurality ofcarriers before an LAA Scell transmission on multiple carriers, whereinthe channel access procedure for each carrier for a physical downlinkshared channel (PDSCH) transmission comprises: first sensing a channelto be idle during slot durations of a defer duration; decrementing acounter and sensing the channel to be idle for an additional slotduration; and sense the channel until either a busy slot is detectedwithin an additional defer duration or all the slots of the additionaldefer duration are detected to be idle; and encode the PDSCH fortransmission on the plurality of carriers, if the channel is sensed tobe idle for at least in a slot duration when the eNB is ready totransmit the PDSCH and if the channel has been sensed to be idle duringall the slot durations of a defer duration immediately before thetransmission, and wherein the memory is configured to store a valueindicating the defer duration immediately before the transmission. 2.The apparatus of claim 1 wherein the processing circuitry is configuredto maintain a common contention window for more than one channel of theSCell.
 3. The apparatus of claim 2 wherein the processing circuitry isto configure the eNB for transmissions over a primary channel of anon-LAA Scell without performing a clear channel access procedure. 4.The apparatus of claim 3 wherein the processing circuitry is configuredto adjust a value for the contention window based on access classpriority.
 5. The apparatus of claim 1, wherein as part of the channelaccess procedure for the LAA Scell transmission, the processingcircuitry is to configure the eNB to sense the channel for a sensinginterval of approximately 25 microseconds (us).
 6. The apparatus ofclaim 1 wherein the processing circuitry comprises a baseband processor.7. The apparatus of claim 6 further comprising: an interface to coupletransceiver circuitry to the processing circuitry.
 8. The apparatus ofclaim 7 wherein the processing circuitry generates baseband signals fortransmission by the transceiver via multiple antennas.
 9. Anon-transitory computer-readable storage medium that stores instructionsfor execution by processing circuitry of an evolved node B (eNB), theeNB configured for Licensed Assisted Access (LAA) secondary cell (Scell)transmissions on multiple carriers, the processing circuitry configuredto: perform a channel access procedure on each carrier of a plurality ofcarriers before an LAA Scell transmission on multiple carriers, whereinthe channel access procedure for each carrier for a physical downlinkshared channel (PDSCH) transmission comprises: first sensing a channelto be idle during slot durations of a defer duration; decrementing acounter and sensing the channel to be idle for an additional slotduration; and sense the channel until either a busy slot is detectedwithin an additional defer duration or all the slots of the additionaldefer duration are detected to be idle; and encode the PDSCH fortransmission on the plurality of carriers, if the channel is sensed tobe idle for at least in a slot duration when the eNB is ready totransmit the PDSCH and if the channel has been sensed to be idle duringall the slot durations of a defer duration immediately before thetransmission.
 10. The non-transitory computer-readable storage medium ofclaim 9 wherein the processing circuitry is configured to maintain acommon contention window for more than one channel of the SCell.
 11. Thenon-transitory computer-readable storage medium of claim 10 wherein theprocessing circuitry is to configure the eNB for transmissions over aprimary channel of a non-LAA Scell without performing a clear channelaccess procedure.
 12. The non-transitory computer-readable storagemedium of claim 11 wherein the processing circuitry is configured toadjust a value for the contention window based on access class priority.13. The non-transitory computer-readable storage medium of claim 9,wherein as part of the channel access procedure for the LAA Scelltransmission, the processing circuitry is to configure the eNB to sensethe channel for a sensing interval of approximately 25 microseconds(us).
 14. An apparatus of a user equipment (UE), the UE configured forLicensed Assisted Access (LAA) secondary cell (Scell) transmissions onmultiple carriers, the apparatus comprising: processing circuitry; andmemory, wherein the processing circuitry is configured to: perform achannel access procedure on each carrier of a plurality of carriersbefore an LAA Scell transmission on multiple carriers, wherein thechannel access procedure for each carrier for a physical uplink sharedchannel (PUSCH) transmission comprises: first sensing a channel to beidle during slot durations of a defer duration; decrementing a counterand sensing the channel to be idle for an additional slot duration; andsense the channel until either a busy slot is detected within anadditional defer duration or all the slots of the additional deferduration are detected to be idle; and encode the PUSCH for transmissionon the plurality of carriers, if the channel is sensed to be idle for atleast in a slot duration when the UE is ready to transmit the PUSCH andif the channel has been sensed to be idle during all the slot durationsof a defer duration immediately before the transmission, and wherein thememory is configured to store a value indicating the defer durationimmediately before the transmission.
 15. The apparatus of claim 14wherein the processing circuitry is configured to maintain a commoncontention window for more than one channel of the SCell.
 16. Theapparatus of claim 15 wherein the processing circuitry is to configurethe UE for transmissions over a primary channel of a non-LAA Scellwithout performing a clear channel access procedure.
 17. The apparatusof claim 16 wherein the processing circuitry is configured to adjust avalue for the contention window based on access class priority.
 18. Theapparatus of claim 14, wherein as part of the channel access procedurefor the LAA Scell transmission, the processing circuitry is to configurethe UE to sense the channel for a sensing interval of approximately 25microseconds (us).
 19. The apparatus of claim 14 wherein the processingcircuitry comprises a baseband processor.